Process for transforming the barium and strontium sulphates



Patented Aug. 5, 1930 UNITED STATES FRITZ ROTHE, OF AACHEN, AND HAENS BRENEK, OF PORZ, NEAR COLOGNE, GERMANY, ASSIGNOBS T RHENANIA VEREIN GHEMISCHES FABBIKEN A. G., 0F COLOGNE, GER- MANY PROCESS FOR TRANSFORMING THE BARI'UM AND STRONTIUM SULPHATES No Drawing. Application filed November 3, 1925, Serial No. 68,641, andin Germany November 12, 1924.

This invention relates to the transformation of alkaline earth metal sulphates into other alkaline earthmetal compounds'and more patricularly to the transformation of barium and strontium sulphates.

The principal object of the invention is the provision of a method for transforming barium and strontium sulphates into desired compounds which is simpler than the known methods in that the intermediate reduction into the corresponding sulphides is eliminated. The said transformation is efiected by mixing the sulphates with silica and heating to high temperatures in the presence of steam.

The usual method of utilizing the bariumand strontium sulphates consists, as it is known, in transforming them by reduction with coal into the corresponding sulfides from which the carbonates, chlorides, nitrates, oxides, hydroxides etc. of said alkaline earth metals can be obtained in a known manner. In these processes hydrogen sulfide is always formed which is generally burnt in the Claus furnace in order to obtain sulphur, as it is ieis ecially known in the case of barium sul- N ow it has been found that said alkaline earth sulphates can be transformed into other alkaline earth compounds in a much simpler way and especially without the formation of sulfides as intermediate products, if the sulphates mixed with silica or materials very rich in silicic acid are heated up to high tem- .peratures in the presence of steam preferably 1n an oxidizing atmosphere. By this manner of operating the sulphur contained in the alkaline earth sulphates is directly obtained as sulfurous acid the further treatment of which occurs in a known manner." The alkaline earth silicate obtained can be utilized in different ways. For instance it may be decomposed by an acid in order to obtain alkaline earth salts. In this case the silica may be again introduced in the process to act upon the sulphates. It is especially advantageous to use the silica in such a quantity with respect to the alkaline earth sulphate that the alkaline'earth silicates obtained are of a type between Me2SiO and Me SiO Under the influence of a treatment with water these alkaline earth silicates split up a part of their alkaline earth as alkaline earth hydroxide, the rest of the alkaline earth re maining bound to the silica as metasilicate.

For instance:

further quantities of alkaline earth sulphates,

then the mixture is heated .to incandescence, as described above, in the presence of steam. By this process orthoor trisilicate or intermediate products between these two silicates are formed again according to the proportion in which the alkaline earth silicate and the alkaline earth sulphate are mixed. This proc-' ess corresponds for instance to the following equation:

BasiOg 2132180 02 BaSiO +2BaSO =Ba SiO +2SO By this manner it is easily possible to obtain barium or strontium-hydroxides, which may either be used in their present state or may be transformed into other bariumor strontium-compounds, for instance into carbonates, chlorides etc. without the necessity to remove the sulphuretted hydrogen, which is formed from the sulphide in the usual process.

The steam required for the reaction may be taken from a'special source and mixed with the heating gases. But it is also possible to heat the furnaces in which the reaction is efi'ected by a fuel very rich in hydrogen which furnishes by its combustion large quantities of steam, as for instance oil, producer'gas from lignites and others.

Example -in a revolving furnace under simultaneous inti'eiiuevien i: sieem eere "being ieken to maintain e'e @Lfidiffiiikg eimespiiere iii the inner fa rness by iniieeiueiilg e suficieni; quantity of en.

The finei preiiiici; leaving the fumeee is exizrseieci "with we'eei by which 36.8% of Bafi is (iiSSOiVQi as beiiumhyii'oxixie. The finei product cenieiiis 83.64% of Bail As inhe mixture is eiieseii to form QBeO-SiU only 41.82% of BM) we be expected. 120 be soluble in Water. Thus the 3%.870 of iheseiubie Bei) obieineei represents 823% (if the iheeretic yieiaii We claim: I 1. The process for trensfoi'ming bariumand strontium-sulphates comprising mixing said; sulphates with silica eni heei-ing seid mixture in an oxidizing atmosphere and in the presence 01? steam te a temperature of at least 1100 C.

29 2. The process for fimnsfei'ming bariumand strontium sulphates comprising miKiI} ms suipheies with siiice and heating sei mixiure in en oxidiizing atmosphere to a tem gei'eiure of at ieesi, 1100 G. by the aid of eating gases containing steam.

3. The process for transforming bariumend stmniium-sui hates comprising mixing saiii sulphates Wii; i siiice in such a 1'0 01"- tion that silicates of s type between iifie iQ 30 end Me SiQQ are formed and heating said mixture in en exiiiizing eimosphei'e semi in the presence of sieem, he a temperature of at least 1100" C.

i. The process for irensferming berium= end strentium-suipiieies comprising mixing said suipiieies with silica in such a propel"- iion thee silicates e? e type between Me i9 aid Me SiQ ere fermei, beefing said mix time in en oxidizing atmosphere emi in the 49 presence of sieem m a iempemtui'e ef ieesi;

119W Q, eiecempesieg the eikeiiiie earth silicetes obtained. by itsesimeni "with meter into eikeiine eeith hyeiiexidies and e reeiflue iiisehiiaie in water consisting esseeisieiiy ei sikeiiee earth meisssiliiceie and introducing seici siiiceie egein iii the process for reacting with ihe seipiiefites. 

